title: Identification and characterisation of C1q-binding phage displayed peptides.
abstract: Five phage displayed peptide libraries were screened for binders to C1q, the recognition subunit of the classical complement pathway. Two rounds of panning resulted in the isolation and characterisation of several different phage displayed C1q-binding peptides from all five libraries. Two groups of the characterised peptides show sequence similarity with part of the metal ion dependent adhesion site (MIDAS) of integrin A-domains, and the site 187LRNPCPNKEKECQPPF of CD18 (integrin beta2), respectively. These results support binding of complement receptor 3 (CR3, CD11b/CD18, Mac1) to C1q and further suggest C1q binding sites in CR3. We also discuss sequence matches between the characterised peptides and proteins known to interact with C1q, as well as other proteins listed in the SwissProt databank. These findings are of interest for the study of the complement system and may lead to the development of peptides, fusion products or peptido-mimetics with C1q modulating potential.
authors.affiliation: Department of Biology, Biotechnology Centre of Oslo, University of Oslo, Norway.
authors.forename: V
authors.initials: V
authors.lastname: Lauvrak
authors.forename: O H
authors.initials: OH
authors.lastname: Brekke
authors.forename: O
authors.initials: O
authors.lastname: Ihle
authors.forename: B H
authors.initials: BH
authors.lastname: Lindqvist
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000302:isolation & purification / Q000378:metabolism*; D002352:Carrier Proteins; D015922:Complement C1q / Q000378:metabolism*; D016384:Consensus Sequence; D006801:Humans; D018960:Hyaluronan Receptors; D008024:Ligands; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D011951:Receptors, Complement / Q000737:chemistry* / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: C087299:C1QBP protein, human; D002352:Carrier Proteins; D018960:Hyaluronan Receptors; D008024:Ligands; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D019151:Peptide Library; D010455:Peptides; D011951:Receptors, Complement; D014764:Viral Proteins; C032402:complement 1q receptor; D015922:Complement C1q